. Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of Greenland and lower California, with which are incorporated General ornithology: an outline of the structure and classification of birds; and Field ornithology, a manual of collecting, preparing, and preserving birds. Birds; Birds; 1887. EXTERNAL I'ARIS OF BIBD8. — TRE FEET. 123 the walking and esj)eciaUy the wading liirds that the crus is most extensively denuded; it may be naked half-way up to
. Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of Greenland and lower California, with which are incorporated General ornithology: an outline of the structure and classification of birds; and Field ornithology, a manual of collecting, preparing, and preserving birds. Birds; Birds; 1887. EXTERNAL I'ARIS OF BIBD8. — TRE FEET. 123 the walking and esj)eciaUy the wading liirds that the crus is most extensively denuded; it may be naked half-way up to the knee. A few waders,—among ours, chiefly in the snipe family,—have the cms apparently clothed to the heel-joint; but this is due, in most if not all cases, to the length of the feathers, for probably in none of them does the ptoryla cruralJs itself extend to the joint. Crural feathers are nearly always short and inconspicuous; ))ut sometimes long and flowing, as in the " flags " of most hawks, and in our tree-cuckoos. The tarsus (I now and hereafter use the term in its ordinary accexJtation— C U> D in fig. '.ii; trs in tig. 36) iu the vast majority of birds is entirely naked, being provided with a horny or leathery sheath of integument like that covering the bill. Such is its condition iu the Fasseres and Piairke (with few exceptions, as among swifts and goatsuckers) ; iu the waders without ex- ception, and in nearly all swimmers (the frigate-bird, Tach)jpetes, has a slight feathering). The liaptores and GalKiios furnish the most feathered tarsi. Thus, feathered tarsi is the rule among owls {Striges); frequent, either partial or complete, in hawks and eagles, as in Aquila, Archibuteo, Falco, Buteo, etc. All our grouse, and perhaps all true grouse, have the tarsus more or less feathered (fig. 35). The toes themselves are feathered in a few birds, as several of the owls, and aU the ptarmigans (Lagopus). Partial feathering of the tarsus is often con- tinued
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbirds, bookyear1887
